In emission control systems of modern internal combustion engines, there are many devices which are operated by vacuum created in the intake manifold. The connection for the vacuum source for such devices is typically taken from one of several locations downstream of the throttle valve in the throttle body. In this source of engine manifold vacuum, there is a high concentration of fuel vapors and other contaminants which are detrimental to the rubber and plastic parts commonly used in vacuum operated devices.
The invention disclosed herein is intended to be used in the vacuum line between the vacuum source and vacuum operated devices to assure that vapors and contaminants never reach the vacuum operated devices.
A similar, more complicated vacuum relay valve for isolating a vacuum operated device from a contaminated vacuum signal source is described in U.S. Pat. No. 3,982,555 issed to Aubel et al and entitled "Vacuum Relay Valve". The valve therein contains both a diaphragm operated poppet valve to open a bleed source to atmospheric pressure and an umbrella valve responsive to vacuum difference between the input and output of the relay valve.
The vacuum check valve of the present invention comprises a single umbrella valve responding to vacuum differences between the input and output of the check valve to direct the output line to feed the vacuum source or to receive reference air through a bleed passage and there is no diaphragm operated poppet valve.
These and other advantages of the invention will become more apparent upon reference to the following detailed description and drawings.